- add slave port for uefi-edk2-bhyve with CSM enabled.
The CSM option was removed from the main port, and
now the port uses different firmware name based on CSM
setting, so master and slave ports can be installed
simultaneously.
- rename destination path: s/uefi-firmwares/uefi-firmware
because "firmware" is plural already
- Use USE_GCC instead of direct dependency
Submitted by: maintainer
Differential Revision: D7157